The invention relates to a tractor for agricultural purposes, especially for seedbed preparation, comprising an engine with a power of at least thirty kilowatts, a frame, at least two power driven wheels, at least one lifting device and at least one power take-off shaft.
In the present development of such agricultural tractors there can be observed a tendency in the following directions:
1. ever larger engines, PA1 2. ever larger wheels requiring a heavier power train, PA1 3. ever heavier tractors, PA1 4. more ballast weight per tractor, PA1 5. more use of heavy cast iron as basic parts of the tractor.
It is overlooked, however, that increasingly heavier tractors adversely affect the structure and the productivity of the soil.
The heavy tractors are compacting the soil excessively. The drainage of the surface water into the soil will be negatively affected. Hard clods will be formed when the soil dries up. This is resulting in a deterioration of the soil structure, decreasing the productivity.
A further disadvantage of the heavier tractors is that the power required by the tractor for moving itself through the field will become higher. Under average field conditions and especially during seedbed preparation and under soft soil working conditions a tractor will use more than fifty percent of its engine power to move itself through the field. This means that less than fifty percent of the engine power will be available at the power take-off shaft. The need for more power requires a larger engine. A heavier engine however increases the tractor weight, which again requires an increase in engine power causing a vicious circle. Therefore the present thinking how to design a tractor is going in the wrong direction. In addition to this consumption of expensive fuel is becoming excessive.